1. Field Of The Invention
This invention relates to a method for improving the color of aroyl chloride compositions.
Aroyl chlorides, such as benzoyl chloride, are used commercially in the manufacture of dye intermediates and of peroxides, such as benzoyl peroxide.
Aroyl chlorides are known to exhibit an undesireable tendency to become discolored during storage. Benzoyl chloride, for example, is a colorless liquid, and in commercial form is typically characterized by a color specification of less than 25 APHA. (APHA denotes a color unit system based on a visual comparison of a sample with standardized aqueous solution of potassium chloroplatinate and cobaltous chloride. The system is described in detail in Standard Methods for the Examination of Water and Wastewater, 15th ed., American Public Health Association, New York, 1981, p. 60-63). Frequently, while in storage or shipment in drums, trailers, tank cars and the like, benzoyl chloride will develop an undesireable color. Although the specific cause of discoloration is uncertain, it is considered that it may be related to the presence of iron or other metal contaminents in the aroyl chloride. Since the off-color material is generally unacceptable, it is often necessary to return and re-distill such material. The additional transportation, handling, and re-distillation may add substantially to the overall cost of the acid chloride. It will be apparent that a need exists for a simple inexpensive method to treat off-color material on-site, and thus eliminate the transportation and other costs associated with return and re-distillation.